The present invention relates to receptor sheets for a manifold paper system, and more specifically, it relates to extremely lightweight receptor sheets which, when utilized with an appropriate donor manifold coating, will provide replicates upon the receptor sheet in a highly visible form with the same speed and having the same color intensity as conventional heavy weight sheets, together with processes for the preparation thereof.
Manifold paper systems have customarily been used in office and plant operations to simplify paperwork operations of billing, invoicing, shipping instructions, and the like. The information has been entered onto these systems by the impact of type or by the pressure of a pen or pencil on the surface. A problem common to all such operations is the pressure that must be applied to obtain the maximum number of legible copies, since the multiple thicknesses of paper used tend to spread out the applied force and thus reduce the pressure on lower sheets. If the manifold pack could be thinned, the pressure needed to produce legible copies could be reduced, or with the same pressure the number of copies could be increased.
Manifold paper systems ae well known, having been introduced into the market place many years ago. They operate through the agency of an oily ink having included therein initially colorless chromogenic reactants in cooperation with a receptor sheet sensitized with substantially insoluble acid-like materials of high surface activity. A typical example of the normally colorless chromogenic material included in the inks is crystal violet lactone and benzoyl leuco methylene blue, both of which, in colored form, have intense hues in the blue spectral band.
Generally, the oil solution of the chromogenic material is encapsulated and coated on a donor sheet, and the donor sheet and a specially coated receptor sheet are placed in physical contact. Upon application of pressure to the donor sheet, the capsules rupture and the oil solution is physically transferred to the receptor sheet whereupon a reaction between the coating on the receptor sheet and the chromogenic material occurs to produce a visible image upon the receptor sheet.
Receptor sheets have been coated with acid-like materials such as clays, resins and the like, and such materials have been predominantly clays with acid sites, such clays as attapulgite, kaolin, bentonite, and halloysite being utilized. Improvements in the clay coatings have been effected by incorporating resins, especially phenolic types, as shown in Brockett, U.S. Pat. No. 3,516,845. Other special coatings using high bulking resins and clays, as demonstrated in Clark, U.S. Pat. No. 3,617,410, have been used, but in all cases, high coating weights have been required.